TTL_VAPERS/TTL_PAPERS Software

This software is now considered obsolete!
The new software is AFAPI, at http://aggregate.org/AFAPI/

[TTL_PAPERS] Simulated Actual

TTL_PAPERS is the TTL implementation of Purdue's Adapter for Parallel Execution and Rapid Synchronization; simple custom hardware that provides very low latency synchronization and communication for parallel processing using clusters of PCs or workstations.
TTL_VAPERS is the Virtual Adapter for Parallel Execution and Rapid Synchronization; a software simulator supporting the development and debugging of parallel programs for TTL_PAPERS using a single UNIX machine.
Both environments are supported by the exact same library code, which is fully public domain. Typical parallel applications can be linked to run in either environment without making any changes to the code.

Why Do I Want This?

Aside from the fact that it is free (fully public domain), you do not need a TTL_PAPERS unit to use the TTL_VAPERS library! In fact, all you need is one machine with a good C compiler (e.g., GCC) and a reasonable approximation to UNIX. For example, running the library demo application, libdemo, you get something like:

This is exactly the same thing you would see using the actual TTL_PAPERS hardware with a cluster of four machines. Well, almost the same. TTL_VAPERS operations average about 100x slower than using TTL_PAPERS... then again, even that is 10x faster than using PVM 3.

If you have X-windows and TCL/TK, you can even watch a graphical representation of the front panel of the simulated TTL_PAPERS unit. The image of the front panel blinks its simulated LEDs just like the real TTL_PAPERS. However, there is more to it: clicking on the simulated front panel invokes a status and control window.

This window provides detailed, automatically updated, status information about the parallel program being simulated. It also provides the user with a variety of debugging controls, including controls to:

Stop execution at the next barrier synchronization; this can be used to stop execution at a key point or even to single-step the parallel program.
Stop/continue/kill the parallel program.
Run a serial debugger (i.e., gdb) on any of the simulated processors.
Alter the UNIX priority of a simulated processor (to simulate a slower or more loaded processor).

As packaged in the archive, things are set so that under a typical installation of Linux you can just unpack the archive, type make, and set a few environment variables. It is a tad more complicated than that on some other systems, but not much worse.

How Do I Get This?

The alpha release of the TTL_VAPERS/TTL_PAPERS library is available as a compressed tar file containing full source code. The full path is:

http://aggregate.org/AFAPI/Archives/TTL_VAPERS/TTL_LIB_950614.tar.Z

The README file within the archive contains notices and instructions for use. More complete documentation is underway.

The only thing set in stone is our name.